1. Field of Invention
Apparatuses and methods consistent with the present invention relate to a display and control thereof, more particularly to a display apparatus with a backlight unit including light emitting diodes (LEDs) which are capable of adjusting brightness for each of illumination regions, and a control method thereof.
2. Description of the Related Art
In recent years, display apparatuses such as liquid crystal display (LCD) monitors that employ backlight units to provide light to liquid crystal display panels are being widely used. The display apparatus can adjust brightness of an image by adjusting the intensity of light emitted from a backlight unit, and can adjust brightness region by region by using a backlight unit that comprises LEDs.
The amount of light emitted from the backlight unit is sensed by a sensor, and color of the light emitted from the backlight unit is kept constant by adjusting ratios of driving current (i.e., duty cycle) supplied to a red color (R) light emitting diode that emits red color light, a green color (G) light emitting diode that emits green color light, and a blue color (B) light emitting diode that emits blue color light, based on the sensed intensity of light.
A range in which the sensor senses the amount of light emitted from the backlight unit is wide. However, if the amount of light is suddenly changed, the sensor may not sense the amount of light precisely due to non-linearity of the sensor that produces about ±5% output errors. The non-linearity of the sensor may cause a phenomenon that color is suddenly changed by change of a screen due to erroneous color adjustment.
For example, if the amount of light is suddenly changed from 100 to 10 on the assumption that the amount of light emitted from the backlight unit is 0 to 100 and the sensor can sense a range of light amount of 10 to 100, the sensor can not sense the light amount of 10 precisely.
For the purpose of overcoming this problem, the conventional display apparatus sets a threshold value of the amount of light emitted from the backlight unit and adjusts color of the light emitted from the backlight only if the amount of light sensed by the sensor exceeds the threshold value.
However, since the backlight unit is much affected by temperature and use time, the amount of light may be decreased by increase of the temperature or deterioration due to extension of use time. If the amount of light is decreased due to deterioration of the backlight unit, and hence the amount of light sensed by the sensor is less than the threshold value, there may arise a problem of non-operation of color adjustment.